Segregation of secondary metabolite biosynthesis in hybrids of Fusarium fujikuroi and Fusarium proliferatum

Gibberellins and the Red Pigments Bikaverin and Fusarubin

“…Remarkably, variations regarding the optimal production conditions may already occur in closely related species. Thus, F. proliferatum wild-type strain D4854 produces fusarubins under acidic culture conditions that were shown to inhibit fusarubin biosynthesis in F. fujikuroi [ 14 ]. Therefore, different regulatory mechanism may apply also for the FSR / PGL biosynthesis gene cluster in F. circinatum and F. oxysporum that did not produce detectable O -methylfusarubin concentrations in our hands albeit the presence of an intact gene cluster [ 16 ].…”

“…Before gibberellin-specifi c genes had been cloned, the biosynthetic pathway was mainly recovered by incorporation studies with 14 C-labeled acetate and mevalonic acid [ 100 , 101 ] as well as by analysis of different UV mutants blocked at certain steps of the biosynthetic pathway [ 102 -105 ]. Later, the genes of the early isoprenoid pathway encoding the three key enzymes of the mevalonate pathway, the hydroxymethylglutaryl coenzyme A reductase (HmgR), the farnesyl diphosphate synthase (FppS), and the geranyl diphosphate synthase (Ggs1) have been cloned [ 106 -108 ].…”

“…The different functions of P450-1 were identifi ed by a combination of two approaches: the deletion of the P450 -1 gene and its insertion into the GA-defi cient F. fujikuroi mutant SG139 that lacks the entire GA gene cluster. While the deletion mutant accumulated ent -kaurenoic acid, cultures of complemented transformants converted ent -[ 14 14 -aldehyde. These data clearly indicate that P450-1 catalyzes four sequential steps in the GA-biosynthetic pathway: 7β(beta)-hydroxylation, contraction of ring B by oxidation at C-6, 3β(beta)-hydroxylation, and oxidation at C-7 [ 118 ].…”

“…The subsequent conversion of GA 14 to GA 4 by the C20 oxidase P450-2 results in loss of carbon C20 and the formation of the fi rst biologically active C19 gibberellin GA 4 [ 120 ] (Fig. 10.2 ).…”

“…Early experiments using 14 C-labeled acetate revealed that the fi rst identifi ed fusarubin-type pigment javanicin also proceeds via the polyketide route [ 126 , 136 ], and incorporation studies using 13 C-acetate suggested a single heptaketide-chain origin for the fusarubins [ 137 ]. The presence of several fusarubins under some and the total lack of all fusarins under different conditions further indicated their origin from a common precursor [ 64 ].…”